A computer virus refers to a set of computer instructions or program codes which are inserted into computer programs by a programmer to destroy computer functions or data, and can influence the use of a computer and be able to self-duplicate. Once a computer is infected with a virus, the files in the computer usually exhibit addition, deletion, modification of a name or an attribute and movement to other catalogue. The operations of the virus on the computer files may lead to a series of problems, such as an normal program being not able to be run, collapse of a computer operating system, the computer being controlled remotely and unauthorized use of user information.
To ensure a safe operation of the computer, it is necessary to search and kill viruses that may infect the files in the system thereby preventing and eliminating the destruction of the viruses. In the security software field, “deleting” and “anti-deleting” the computer files infected with a virus is one of eternity subjects of a confrontation between a security software and a malignant program (computer virus). Usually, a virus in the prior art may apply a encryption lock to a file infected with a virus by means of occupying a file handle, setting a file attribute to be read-only and keeping the file in a deleted status and so on. The encryption lock cannot be cracked (that is the file infected with the virus cannot be deleted) by conventional means. These means can prevent an antivirus software from cleaning the file infected with the virus. The procedure of killing the virus by the security software may be regarded as unlocking and crushing a virus file. A current security software having simple means for unlocking and crushing the virus file cannot relieve the obstructions set by the virus file and have a weak confrontation capability.